It is known to hydrohalogenate a feed rich in straight chain terminal olefins, or alpha olefins, to produce hydrohalogenated alkanes comprised predominantly of straight chain alkyl groups particularly useful in the production of linear tertiary amines, or alkyl dimethyl amines. As a class the linear tertiary amines are useful as surface active agents, e.g., surfactants, soaps, cleansing and other personal care products.
It is also known to produce linear tertiary amines, or alkyl dimethyl amines, starting with a mixed olefin feed, viz., vinyl olefins and internal olefins, or vinyl olefins and vinylidene olefins, or admixture of vinyl olefins, internal olefins and vinylidene olefins. U.S. Pat. No. 4,024,189, which was issued on May 17, 1977 to Wayne T. Davis, describes a process of this type. In a first step, where vinylidene olefins are present in appreciable quantities, the feed is generally selectively isomerized to convert the vinylidene olefins to branched chain internal olefins. The admixture of vinyl olefins and internal olefins is, in either event, next hydrohalogenated. Suitably, the admixture of olefins is hydrohalogenated at conditions which promote the AntiMarkovnikoff addition of the hydrogen halide to the olefin. In the production of linear tertiary amines from a mixed olefin feed, it is essential after the hydrohalogenation step to separate the 1-haloalkanes from the secondary and tertiary haloalkanes, and thereby concentrate the 1-haloalkanes prior to amination of the 1-haloalkanes to form aminehydrohalides. The aminehydrohalides are then neutralized to convert them to linear tertiary amines.
The 1-haloalkanes are concentrated in a stream for subsequent amination, and neutralization, by selective dehydrohalogenation. Thus, the feed constituted of an admixture of primary, secondary and tertiary haloalkanes, or bromoalkanes, is next selectively dehydrohalogenated, or dehydrobrominated. In the reaction, the hydrogen halide, or hydrogen bromide, is removed from the reaction mixture by sparging with nitrogen. The mixture of olefins and alkylhalides, or alkylbromides, is then subjected to a separate distillation to remove the olefins, and the alkylhalides, or alkylbromides, and then recovered.
A straight chain olefin, particularly an alpha olefin, is the raw material of choice in conducting this process because the surface active properties of a straight chain derivative thereof is superior for a given molecular weight vis-a-vis their branched chain isomers. Substitution in the 1-position of the alpha olefin yields more stable and effective products. For this reason, in the production of alkyl dimethyl amines it is sometimes current practice to use a blended olefin feed constituted essentially of alpha olefins as the raw feed. Because of the relatively high cost of high purity alpha olefin feeds vis-a-vis the lower cost and greater availability of mixed olefin feeds however, there exists a clear present need for processes which can economically handle mixed olefin feeds.